Skip pages without revisions in forceSearchIndex

Without this pages without revisions would cause forceSearchIndex to crash
as it checks if they are redirects.  This is logged at the normal output
level because it isn't really an error, more of a warning.

Bug: 56965
Change-Id: I68d79278a0932ae18db73203c3730165cdc3e398
Merge "Skip pages without revisions in forceSearchIndex"